JPH10137913A - Plunger for die casting and using method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plunger for die casting having a suitable structure to the needs of profitability and saving of the resources without wastefulness of raw material and machining, in the plunger for die casting having complicated shape and needing precise machining. SOLUTION: In the plunger 1 for die casting composed of a plunger tip 2 for sliding in a sleeve as a molten metal flowing passage and a rod 3 connected with the front end of the plunger tip 2, the plunger tip 2 is composed of a tip body 4 having a cylindrical shape and a cylindrical ring 5 fixed to the outer periphery of this tip body and forming a sliding surface to the sleeve, and this cylindrical ring 5 is constituted so as to be changeable to the tip body 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plunger used for die casting, which is a casting method in which a molten metal is pressed into a mold by applying pressure to the molten metal, and a method of using the same.

[0002]

2. Description of the Related Art Die casting uses a precision mold, and a molten metal (molten metal) is automatically or manually poured into a sleeve, and pressure is applied to the molten metal with a plunger tip to inject the molten metal into the mold. It is a method of casting products. According to the die casting method, since it has high accuracy and hardly requires any mechanical finishing, it is suitable for mass production and widely used for manufacturing parts such as automobiles, communication equipment, daily necessities, cameras and the like.

[0003] Such a plunger for die casting,
It consists of a plunger tip that slides in a sleeve that serves as a molten metal flow path, and a rod that is screwed to the rear end of the plunger tip, and reciprocates in the sleeve for each casting by hydraulic pressure or the like. The material of this plunger tip is beryllium, which is usually excellent in heat resistance and wear resistance.
A copper alloy or a steel for a hot mold, or a material subjected to a surface hardening treatment such as a nitriding treatment or a thermal spraying treatment to form a protective layer having a smooth sliding property on the surface thereof is used.

[0004]

However, in a general die casting apparatus, especially in continuous casting, when the number of times of casting exceeds a predetermined value, a nitriding treatment such as SKD61 having excellent heat resistance and wear resistance as described above is used. Even if it does, the surface of the plunger tip that slides inside the sleeve is roughened or partially worn by the influence of heat or molten metal, resulting in poor movement. In such a case, conventionally, the entire plunger that has become poorly moved is removed and discarded, and a new plunger is attached to continue casting. However, when only the plunger tip surface is worn or roughened so that it cannot be used, discarding the entire plunger and replacing it with a new one wastes the usable metal material part and saves it. Unfavorable on resources, especially SK
D61 and beryllium-copper alloy are expensive, and replacing them with new ones is disadvantageous in cost and wasteful in terms of economy.

[0005] If an inexpensive material is used in consideration of such economic efficiency, the chip surface becomes rough and abrasion becomes severe.
If it becomes unusable in a short period of time and the productivity is reduced, and if the use period in a rough state is prolonged, the entire device is deteriorated, the life is shortened, and the quality of the product is reduced.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-mentioned prior art, and in a die casting plunger including a cooling water circulation chamber and the like, which requires complicated and precise machining, it is possible to eliminate waste of material and machining, and to reduce the cost and economy. An object of the present invention is to provide a die-casting plunger having a structure suitable for resource saving requirements and a method of using the same.

[0007]

In order to achieve the above object, the present invention provides a plunger tip which slides in a sleeve serving as a molten metal flow path and a rod connected to a rear end of the plunger tip. In the die casting plunger, the plunger tip comprises a tip body having a cylindrical shape, and a cylindrical ring having excellent heat and wear resistance, which is fixed to the outer periphery of the tip body and forms a sliding surface for the sleeve. The present invention also provides a die casting plunger characterized in that the cylindrical ring is configured to be replaceable with respect to the tip body.

According to the above construction, when the plunger tip surface becomes rough due to use and the movement becomes poor, the tip body can be left as it is, and only the cylindrical ring on the surface can be replaced, resulting in wasteful disposal of material. This contributes to resource saving and is economically advantageous. In addition, by replacing only the cylindrical ring in this way, it is possible to form only this ring with an expensive material having excellent heat resistance and abrasion resistance, thereby reducing costs without deteriorating quality. Can be. In addition, since excellent materials can be used at low cost, the frequency of component replacement is reduced, productivity is increased, and the life of the apparatus is extended, thereby improving quality.

As a material of the replaceable cylindrical ring, for example, hot die steel (SKD61) having excellent heat resistance and wear resistance, or further, a surface hardening treatment such as thermal spraying or nitriding treatment is applied to the SKD61. , A composite metal material such as a beryllium-copper alloy or a cermet, or an expensive material such as a cemented carbide material or a ceramic material.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a main part of a die casting plunger according to an embodiment of the present invention. FIGS. 2 and 3 are rear (rear) and front (front) views of the plunger chip, respectively. It is.

The die casting plunger 1 comprises a plunger tip 2 and a rod 3 connected to the rear end. The plunger tip 2 is composed of a tip body 4 having a cylindrical side surface and a cylindrical ring 5 exchangeably mounted around the tip body 4. A cooling water circulation chamber 6 is formed inside the chip body 4, and a screw 4a is formed on the inner surface of the inlet. The rod 3 is screwed and fixed to the chip body 4 by screwing a screw 3a formed at an end thereof to a screw 4a of the chip body 4. At this time, the rod 3 is firmly screwed to the chip body 4 using a spanner hook 7 provided at the rear end of the chip body 4. A reciprocating cooling water passage 8 communicating with the cooling water circulation chamber 6 is formed inside the rod 3.

A flange-shaped head 9 is formed at the front end of the chip body 4 and a step 10 is formed at the back side thereof.
The cylindrical ring 5 comes into contact with the step portion 10,
The ring 5 is prevented from dropping forward of the chip body 4. A screw 4b is formed on the outer periphery of the tip body 4 on the rear end side of the ring 5, and a nut 12 in the form of a double nut is screwed to the screw 4b. With these nuts 12, the ring 5 is pressed against the step portion 10 of the chip body 4 and is firmly screwed and fixed. At this time, an appropriate tool is inserted into the hole 13 for tightening the nut, and the nut 12 is rotated to firmly tighten. As a result, the ring 5 is firmly fixed and held on the chip body 4 without displacement or falling off. When the nut 13 is assembled to the die casting machine, the mounting rotation angle of the plunger tip is adjusted so that the nut 13 is mounted downward so that molten metal does not enter.

As a means for fixing the ring 5 to the tip body 4, instead of the above-described method using the double nut 12, a shrink fit method or a screw-in method may be used.
In this way, by directly fixing the ring to the chip body, it is possible to prevent the occurrence of play between the ring and the chip body due to the difference in thermal expansion based on the temperature difference between the center and the outer periphery of the chip. The ring can be fixed on the tip body.

A key 11 is mounted between the tip body 4 and the ring 5 to prevent mutual rotation. This key 11 is desirably provided on the rear end side of the chip body 4 as shown. This is because, if provided on the tip of the plunger, the tip is subjected to the greatest load, and the key itself or the tip body may be deformed. However, if there is no problem in terms of heat or strength, the chip may be provided on the circumferential back surface of the flange-shaped head 9 on the tip end side of the chip body 4 from the viewpoint of workability. In particular, in the case of a small plunger tip, this key may not be provided.

Further, the key groove is provided at a position divided into two, three, four or more on the circumference, and when the circumferential side surface of the ring becomes worn or rough,
The use of the same ring may be continued by changing the mounting rotation angle of the ring by changing the keyway position. That is, in general, the plunger tip is largely worn on the front end side directly in contact with the molten metal having a large thermal influence and on the lower surface side in contact with the lower side of the sleeve in which the molten metal is accumulated. In this manner, when uneven wear on the tip side and lower surface side of the tip is observed, the circumferential side surface of the ring is uniformly worn by changing the rotation angle of the ring to effectively utilize the ring material. The service life can be extended. In this case, the service life can be further extended by changing the direction of insertion of the ring in the front-rear direction.

The ring 5 is rotatably mounted on the tip body 4 without providing the key 11, so that the ring naturally rotates during use, preventing uneven wear of the peripheral side surface and preventing the ring side surface from being unevenly worn. Uniform wear can be achieved.

The material of the chip body 4 is, for example, SK
D61 is used. As a material of the ring 5, for example,
Hot mold steel (SKD6) with excellent heat resistance and wear resistance
1) Alternatively, a material obtained by subjecting this SKD61 to a surface hardening treatment such as thermal spraying or nitriding treatment, a composite metal material such as a beryllium-copper alloy or a cermet, or an expensive material such as a cemented carbide sintered material or a ceramic material; Other thermal spray metals can be used.

The metal for thermal spraying is a metal material which has been conventionally thermally sprayed or welded on the chip surface. For example, the main component is Ni, Cr, B, Si or Mo added thereto to provide excellent wear resistance. Co, Cr, B,
A self-fluxing alloy having excellent heat resistance, such as Si and Mo, is used.

FIG. 4 is a structural view of a cold chamber die casting machine to which the present invention is applied. The fixed board 18a and the movable board 18b are installed on the base frame 30. A fixed die 19a and a movable die 19b are respectively attached to the fixed plate 18a and the movable plate 18b so as to face each other. The movable plate 18 b can reciprocate along the tie bar 20 by the mold clamping cylinder 29. This movable plate 18
b, the push rod 27 connected to the push cylinder 28
And an extruding plate 26 are attached. A plurality of push pins 25 are provided to protrude from the front surface (right side in the figure) of the push plate 26.

On the other hand, a sleeve 21 is mounted on the fixed board 18a. An end (right side in the figure) of the sleeve 21 protrudes from the fixed plate 18a, and a gate 14 is formed on the upper side thereof. In this sleeve 21,
The plunger 1 including the plunger tip 2 and the rod 3 according to the present invention is mounted. The rod 3 is connected to a piston rod 23 of the injection cylinder 22 via a coupling 24.

In the casting operation by the die casting machine having the above-described structure, first, the movable plate 18b is moved along the tie bar 20 toward the fixed plate 18a by the mold clamping cylinder 29, and the movable die 19b is pressed against the fixed die 19a. The mold is clamped to form a cavity between the two dies corresponding to the molded product. In this clamped state, molten metal (molten metal) is injected from the gate 14 of the sleeve 21.

Subsequently, the plunger tip 2 is pushed into the sleeve 21 by the injection cylinder 22 via the piston rod 23 and the plunger rod 3, and the molten metal is injected into the cavity through the molten metal passage 17 to fill the cavity with the molten metal. I do.

When the molten metal injected and filled in the cavity is hardened, the movable plate 18b is moved away from the fixed plate 18a, the movable die 19b and the fixed die 19a are opened, and the extrusion rod 28 and the extrusion rod 27 are pushed by the extrusion cylinder 28. Board 2
6, the extrusion pin 25 is projected into the cavity,
Extrude the product from the mold. This completes one cycle (one shot) of the casting operation. By repeating such a casting operation, a die cast product can be obtained continuously.

When the number of times of casting reaches a certain number or more, the surface of the plunger tip 2 of the plunger 1 is unevenly worn or rough due to heat of the molten metal and friction with the sleeve, as described above, so that the sliding operation is smooth. The movement becomes worse. In this embodiment, such a state is a state in which the surface of the ring 5 attached to the tip body 4 of the plunger tip 2 is worn or roughened and deteriorated. Therefore, when such a state occurs, the nut 12 (FIG. 1) attached to the chip body 4 is removed, the deteriorated ring 5 is removed, this is replaced with a new ring, and the chip 5 is attached to the chip body 4 again. ,
The nut 12 is fixed and held. As a result, only the worn or rough sliding surface can be renewed while the chip body 4 is left, and the new material can be renewed only by replacing a small amount of the material in the sliding portion without wasting material. The same smooth sliding operation as the product is achieved.

The circumferential side surface of the worn ring 5 is ground and regenerated as a reduced-diameter plunger tip in which the unused heat-resistant and wear-resistant material is exposed as in the new product. It can be reused by attaching it to a sleeve having a diameter suitable for. Or, after grinding the circumferential side,
The ring diameter can be enlarged by thermal spraying or welding, returned to the original ring diameter, and reused with the same die casting machine.

FIGS. 5 to 8 show a plunger tip according to another embodiment of the present invention. FIG. 5 is a sectional view of the chip body, FIG. 6 is a sectional view of a ring mounted on the chip body, and FIG.
FIG. 8 is a front view of the ring of FIG. 6, and FIG. 8 is a cross-sectional view of an assembled state of the plunger tip. This plunger tip is
As shown in FIG. 6, a screw 5a is formed on the inner surface of the rear part of the ring 5, and the screw 5a is used to fix the ring 5 to a screw 4b provided on the chip body 4 in FIG. After the ring 5 is mounted on the chip body 4, as shown in FIG. 8, the key 32 is driven to prevent the rotation of the ring 5, and then the nut 12 is screwed to fix the ring 5 on the chip body 4. I do. The ring 5 has a spanner hook 31 for attaching and detaching work.
Is desirably formed. It is also desirable to provide a wrench hook 30 for attaching and detaching work on the chip body 4 in the same manner. The key 32 for preventing rotation can be omitted, and there is no problem even if it is omitted particularly in the case of a chip having a small diameter.

As described above, by attaching the ring 5 to the chip main body 4 by screwing, the attaching / detaching operation at the time of replacing the ring, particularly the operation of removing the worn ring can be easily performed.

[0029]

As described above, in the present invention, when the plunger tip surface is unevenly worn due to use or roughened due to the thermal influence of the molten metal, and the movement becomes poor, the tip body constituting the inside of the chip is Only the cylindrical ring that covers the outer peripheral side surface can be replaced, and wasteful disposal of the material is prevented, which contributes to resource saving and is economically advantageous. Further, by replacing only the cylindrical ring in this way, only this ring is subjected to thermal spraying or nitriding treatment on, for example, hot mold steel (SKD61) excellent in heat resistance and abrasion resistance, or further on this SKD61. It can be formed using a material that has undergone a surface hardening treatment, such as a beryllium-copper alloy or a cermet, or an expensive material such as a cemented carbide material, a ceramic material, or other metal for thermal spraying. It is possible to use a less expensive material as the material of the internal chip body. Thereby, cost can be reduced without lowering the quality. In addition, since excellent materials can be used at low cost, the frequency of component replacement is reduced, productivity is increased, and the life of the apparatus is extended, thereby improving quality.

This makes it possible to recycle necessary parts in the manufacturing process of the cast product, stably keep costs low irrespective of constantly changing economic conditions,
The limited resources can be effectively used to save material and contribute to the development of the entire industry.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a main part of a die casting plunger according to an embodiment of the present invention.

FIG. 2 is a rear view of the tip body of the plunger of FIG. 1;

FIG. 3 is a front view of the tip body of the plunger of FIG. 1;

FIG. 4 is a basic configuration diagram of a die casting apparatus to which the plunger of FIG. 1 is applied.

FIG. 5 is a sectional view of a chip body according to another embodiment of the present invention.

FIG. 6 is a sectional view of a ring mounted on the tip body of FIG. 5;

FIG. 7 is a front view of the ring of FIG. 6;

8 is a cross-sectional view showing a state where the ring of FIG. 6 is mounted on the chip body.

[Explanation of symbols]

1: plunger, 2: plunger tip, 3: rod, 4: tip body, 5: ring, 9: flanged head, 10: step, 11: key, 12: nut.

Claims (4)

[Claims] 1. A die casting plunger comprising: a plunger tip that slides in a sleeve serving as a molten metal flow path; and a rod connected to a rear end of the plunger tip, wherein the plunger tip has a cylindrical shape. And a cylindrical ring fixed to the outer periphery of the chip body and forming a sliding surface against the sleeve and having excellent heat resistance and abrasion resistance. The cylindrical ring is replaceable with respect to the chip body. A plunger for die-casting characterized by comprising. 2. The method according to claim 1, wherein the cylindrical ring is SKD61, SKD.
The plunger for die casting according to claim 1, wherein the plunger is made of a material obtained by subjecting 61 to a surface hardening treatment, a beryllium-copper alloy, a cermet, or a superhard ceramic. 3. A method for using a die casting plunger comprising: a plunger tip sliding in a sleeve serving as a molten metal flow path; and a rod connected to a rear end of the plunger tip. A chip body having a cylindrical shape, and a cylindrical ring fixed to the outer periphery of the chip body and forming a sliding surface with respect to the sleeve. After a predetermined number of uses, the cylindrical ring is removed from the chip body and newly formed. A method of using a die-casting plunger, wherein the chip body is reused by mounting a simple cylindrical ring. 4. When the surface of the cylindrical ring is locally worn or roughened, the cylindrical ring is further used by changing the rotation angle of attachment to the tip body, and thereafter, the cylindrical ring is replaced with a new cylindrical shape. 4. The method according to claim 3, wherein the plunger is replaced with a ring.